Dry Stone Walling

Dry stone walls are a familiar sight to almost all of us, whether we live among them or associate them with perceptions of place or time, we are certainly aware of their existence. Although most of the walls we see today date back to the 18^th or 19^thcentury and the establishment of enclosure acts and the consequent dividing of common land across the country, dry stone walling has far more ancient foundations. Who knows when the first aspiring builder stacked some loose rocks up to create a wall in this fashion? Or whether the wall was even the first form constructed in dry stone? Scientists tell us they were in use in the bronze and iron ages. However old they are, the fact that they belong to the landscapes in which they stand is instantly discernible. Such iconic structures, although low key in appearance and colour, the walls express a great deal. They speak of the geology of the land, not just in the type of stone, but the size, shape and texture all tell part of the story, maybe the stone was gathered from the adjacent field, as is often the case, maybe it was chipped away from the mountainside. The solid stance visualises the hard work involved in working a wall, a tonne of stone involved every few feet or so. A wall is synonymous with a boundary and the height provides an insight into the variety of livestock it may have intended to hem in. In some cases it was to deter humans, in the middle ages they were even know to line the peaks of the Pennines as a symbol of territory.

In the study of vernacular building in Britain I think dry stone construction is highly relevant, it provides a great perspective for historical study, few things can be suspected to link back to the anthropologic origins of our island like these structures. Again there is also the tie to the land and rural life, of which the language provides a unique insight, with groups of synonyms such as, Sheep Creep, Hogg Hole, Sheep Smoose, Lunkie and Thirl, all describing the hole bridged over by a wall to allow the passing of livestock from one field to the next.

On closer inspection the perspective of other occupants of the land can be gained. What fantastic habitats these walls make for a large range of wildlife. Home for insects and small mammals, the walls also offer valuable shelter from the elements to larger animals such as foxes or sheep. They even provide the inhabitants with a source of thermal mass, no eco-bling required.

I’m interested in the use of dry stone construction in contemporary design but as this post swells I think I’ll leave that particular can of worms for another time. I will also resist venturing into discussion of construction as I think this is best done via regional research, given the varying local nature of the walls.

So it is with dreams of Sheep Creeps, Cripple holes and Water Smoots that I look forward to further inquiries into this ancient past time.

A Sheep Creep

Djenné and Sustainability

When analysing mud building, the fact that the construction footprint (including transport of materials) is little bigger than the footprint of the site itself is surely the pinnacle of sustainable construction. In Djenné the buildings are predominantly flat roofed, wooden beams spanning the mud walls, covered with mud. With the source of wood being the slow growing palm trees indigenous to the area, this system brings the sustainability aspect into question. In the case of the mosque, which is currently undergoing restoration, I think 100 years of use more than matches up to the growing rate of the palms. But as far as the town as a whole is concerned there is the issue of erosion in the desert due to the removal of trees that will need to be addressed, especially given the town’s delicate relationship with the Niger. It will be interesting to see how the traditional building techniques of the town’s people evolve to answer this problem. I’ve heard various suggested solutions including the Nubian vault, as coined and revived by Hassan Fathy, constructed without the need of timber framework and utilising the adobe bricks already in use, which are of course plentiful. But what are the consequences of introducing an outside technique? Does this in some way dilute the vernacular purity? Whatever happens a tree-planting project is due, I wonder if the Aga Khan Trust have plans to implement such a precaution. If so I think maintaining it could be the greater challenge.

An ancient technique, the Nubian Vault is constructed in layers of mud bricks without the need of wooden framework (conventional arches and vaults are normally supported by a timber frame until the keystone is set in place at the apex). Building horizontally off a vertical wall each layer of brick is angled and so supported by the previous layer.

Nubian Vaults under construction.

Djenné

Djenné (jen-nay) is a settlement in the West African country of Mali. Situated on the river Niger, which provides both life and constraints. Every year the river floods, something that is an integral part of the town’s yearly eco-cycle. Djenné is positioned in such a way that when the river does flood it becomes almost an island. This prevents any further growth outside of the current footprint so any development must happen within the current town walls.

Djenné is most famous for the Great Mosque, built entirely of mud (with the exception of the wooden roof beams). The original mosque dates back to around 1250 but the mosque that stands today is a reconstructed version, erected in about 1907 by the French. The former didn’t simply collapse but had its drainage system sabotaged, allowing water to build up during the heavy rain season and overpower the building. The mosque is now listed by UNESCO as a world heritage site and the Aga Khan Trust for Culture is working on restoration.

The Great Mosque, Djenné

One of the wonderful things about mud architecture, whether of the compressed earth or adobe brick variety, is that the buildings essentially emerge from the ground on which they stand. As a general rule for Mali towns, materials are collected from within 1.5 miles of the site. Towns not so far away from Djenné lie in a more rocky part of the desert and so rocks are gathered and incorporated into the building. In Djenné itself one of the techniques that has developed over hundreds of years is the tradition of using small, hand pressed cylindrical bricks. I think this is testament to the lack of outside influences, despite being historically significant as a commercial hub. Not being the most structurally sound solution, they remain a popular choice. The nature of mud architecture dictates that supporting columns are very regular and open floor space is limited, plans read almost like a chess board, but this is simply accepted and worked with.

Masons are central and respected figures in Mali society but in general most people possess building skills. Building extensions/alterations etc, fairly regular practice, are done by the occupying family themselves. Lumps of palm wood project from the larger facades, including those of the mosque, serving as reinforcement, decoration and built-in scaffolding.

Every year there is an event in Djenné that encapsulates the relationship between the inhabitants and the architecture and more specifically, the mosque: The re-plastering of the Great Mosque. Early in the rain season this huge but brief event takes place. It’s become a kind of communal, spiritual, joyous celebration. Everyone wants to take part, so much so that they now allocate areas of the building to areas of the town to ensure everybody is able to get involved. People swarm all over the building, enabled by the palm tree poles cantilevering from the façade, acting as permanent scaffolding. Top to bottom, the whole building is complete in about half a day. When I first heard about this I was keen to participate, or even simply observe, but the date is not marked in any calendar or planned too far in advance specifically to avoid the likes of me turning up, which I think is a very good thing. Nevertheless Mali remains my top research destination.

Re-Plastering of The Great Mosque.